Eye tracking device and method for manufacturng an eye tracking device

ABSTRACT

The invention relates to an eye tracking device comprising one or more illuminators, each illuminator comprising a light emitting side, and each illuminator being connected to a first circuitry carrier, an imaging module connected to a second circuitry carrier wherein the image module comprises optical arrangements. The plurality of illuminators, the imaging module and the circuitry carriers are embedded without gaps in a first material. The invention further relates to methods for manufacturing an eye tracking device with over-molded components.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims benefit to Swedish patent application No.1850724-4, filed on Jun. 13, 2018, to Eli Lundberg, Richard Hainzl andDaniel Tornéus, entitled “Eye tracking device and method formanufacturing an eye tracking device”, and is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present invention relates to a device for eye tracking and a methodfor manufacturing an eye tracking device. More specifically, thedisclosure relates to a device with one or more illuminators and amethod according to the introductory parts of claims 1 and 18.

BACKGROUND ART

The illumination solutions in eye tracking devices are in an early stageof development. Many solutions are more or less development kits thatare very simple. For device in glasses mechanical carrier rings and aflexible PCB with a number of Light Emitting Diodes (LED) are usuallyprovided. The ring holds the LEDs in the correct position and anglesthem towards the eye of the user. The flex PCB is attached to the ringwith a glue.

More advanced device types use several mechanical plastic parts and oneflex PCB. One part may be used for mounting the flex, called Carrier.Another NIR transparent part is used to cover and protect the LEDs onthe flex, called LED Cover. Preferably this part is opaque to visiblelight to make it more attractive esthetically.

The LED cover needs to have good optical properties and there are somedesign challenges. It is important that it doesn't act like a lightguide and it should not cause the light to illuminate the eye thoughdifferent optical paths. There are tough tolerances on the mechanicalparts and assembly to ensure good optical performance and also goodesthetical fit. The LED placement have very tight tolerances due to thatoffset can create either stray light or significantly diminishillumination level and loss of the glint.

In both cases the LED flex can be angled to increase efficiency and alsoreduce stray light but this makes the assembly process more difficult,possibly requiring human based assembly which increases cost and lowersyield.

There is thus a need for solution that make the assembly easier forlarge volumes providing precise tolerances. It is also a desire in theindustry to enable smaller and more advanced form factors as the eyetracking devices are integrated in small structures as frames forglasses etc. A further problem is that previous solutions have gapbetween plastic parts causing problems with stray light and impreciseoptical properties. Gaps in the assembly are also not estheticallyattractive. Previous solutions are also more fragile as glued ormechanically joined parts break easily.

SUMMARY IF THE INVENTION

It is an object to mitigate, alleviate or eliminate one or more of theabove-identified deficiencies in the art and disadvantages singly or inany combination and solve at least the above mentioned problem.According to a first aspect there is provided an eye tracking devicecomprising one or more illuminators, each illuminator comprising a lightemitting side, and each illuminator being connected to a first circuitrycarrier. An imaging module is connected to a second circuitry carrier,the image module comprises optic arrangements. The plurality ofilluminators, the imaging module and the circuitry carriers are embeddedwithout gaps in a first material. This solution provides smaller devicesas the assembly is easier to automate. The assembly is also more preciseproviding less variations in the manufacturing. This solution alsoprovides an eye tracking device that is free from gaps enhancing opticalperformance and provides better looking and more robust devices. If thefirst material is transparent to the radiation from the illuminators theilluminators and optionally also the image module may be embedded in thefirst material.

According to some embodiments the first material comprises openings suchthat at least one of the light emitting sides of the illuminators andviewing portion of the optic arrangements of the imaging module are notcovered by the first material. If the first material is not transparentto the irradiation from the illuminators openings for the illuminatorsand/or the image module has to be present.

According to some embodiments at least one of the openings of the firstmaterial are filled with a second material that is transparent for thelight of the illuminators. In this way an integrated window can becreated for the illuminator light source and/or imaging module.

According to some embodiments the first material is non-transparent tothe illuminator light to stop light from the illuminator to propagate incertain angles. The non-transparent first material also provides a framefor the circuit carrier that visually hides the circuits from the userof the device providing a more attractive design.

According to some embodiments at least the first material is shaped inthe form of one of the frames of a pair of glasses so as to provide adevice usable for Augmented Reality (AR) applications or Virtual Reality(VR) applications.

According to some embodiments all illuminators are connected to a singlefirst circuitry carrier so as to minimize the number of components.

According to some embodiments the first circuitry carrier and/or thesecond circuit carrier is a Printed Circuit Board or a 3D moldedinterconnect devices. According to some embodiments the imaging moduleis a camera or a lens-less camera or any other imaging device.

According to some embodiments the second circuitry carrier is anintegral part of the first circuitry carrier so as to further minimizethe number of components of the device.

According to some embodiments the openings are formed as apertures tolimit illuminator light emitting angles. This is advantageous in VRapplications so that the illuminators do not disturb the eye image dueto light going into the lens creating stray light that obfuscate the eyein the image captured by the image module.

According to some embodiments the illuminators are front emitting tomaximize light emittance in the frontal direction of the illuminators orside emitting to avoid light emittance in certain directions from theilluminators.

According to some embodiments the first circuitry carrier and/or thesecond circuitry carrier is flexible to make the automated assemblyeasier or to enable a flexible design of the eye tracking device.

According to some embodiments the illuminator is a radiation sourcecomprised in the group of: a LED, a laser, an incandescent lamp and afluorescent material. The smallest, most robust, most energy efficientand cheapest solution is preferably used. A LED is therefore preferredin the current industry but developments in light sources may call foranother radiation source. According to some embodiments the illuminatorsare Near Infrared (NIR) illuminators. This is advantageous as NIRradiation is not visible to the human eye.

According to some embodiments, the second material is transparent to IRlight but non-transparent to visible light. In that way the moldedwindows for the illuminators and/or the image module can be made opaquefor the user which provides extra freedom in design possibly making thedevice more attractive.

According to some embodiments the second material is an opticalarrangement so as to enhance the optical properties sin a certain way.It could e.g. be a lens shape to forma positive or negative lens. It mayalso be a pattern forming a Fresnel lens or any other similar shapegiving a lens effect.

According to some embodiments the first material is PMMA, PC, Zeonex orABS with or without added pigments that are transparent to NIR, and/orthe second material is PMMA, PC, Zeonex or ABS with added pigments thatare non-transparent to NIR.

According to a second aspect there is provided a method formanufacturing an eye tracking device, comprising the steps of: providinga plurality of illuminator, each illuminator comprising a light emittingside, and each illuminator being connected to a first circuitry carrier,providing an imaging module connected to a second circuitry carrier, theimaging module comprising a lens for capturing images of an eye,embedding the plurality of illuminators, the imaging module and thecircuitry carriers without gaps in a first material, wherein the firstmaterial comprises openings such that the light emitting sides of theilluminators and the imaging module lens are not covered by firstmaterial. Increased yield in production may be achieved due to fewer andsimpler steps then in the prior art manufacturing with often manualassembly of mechanical parts. The manufacturing method also enables thatit becomes simple to change the design of the eye tracking device usingthe same PCBs and image module.

According to some embodiments the method further comprises the step offilling at least one of the openings of the first material with a secondmaterial that is transparent for the light of the illuminator.

According to some embodiments the step of embedding comprises: providinga first mold, placing the first circuitry carrier and second circuitrycarrier in the first mold, filling the empty space of the first moldwith the first material. This is a process that is suitable forautomated assembly.

According to some embodiments the mold comprises first structures forpreventing the first material to cover the light emitting side of theilluminators and a second structure for preventing the first material tocover the imaging module. In that way the first material may be moldedwithout covering the illuminators and imaging module. The secondmaterial may then be molded into the empty openings in the firstmaterial being a consequence of the illuminators and imaging modulepreviously being covered by the first structures and the secondstructures.

According to some embodiments, the mold comprises alignment features foraligning the first structures and the second structure with theilluminators and imaging module, respectively. By exactly fixating thefirst circuitry carrier and second circuitry carrier in the first mold aprecise fit is always accomplished so that the components are alwaysplaced in the same exact way for every manufactured device.

According to some embodiments the method further comprises the step offilling at least one of the openings with a second material that istransparent for the light form the illuminators.

According to some embodiments, the step of embedding comprises:providing a second mold with empty spaces aligned with the lightemitting sides of the illuminators and the viewing portion of theimaging module, placing the first circuitry carrier and second circuitrycarrier to the mold, filling the with the second material, such that atleast the light emitting sides of the illuminators and the viewingportion of the imaging module are embedded in second material, providinga first mold, placing the first circuitry carrier and second circuitrycarrier in the first mold, filling the empty space of the first moldwith the first material. In this way the second material, intended to betransparent window to the illuminators, is applied firstcovering/encapsulating the illuminators and/or the image module. In thatway there is no risk of by mistake covering the illuminator and/or imagemodule with the first material that is non-transparent for the radiationfrom the illuminator(s).

According to a third aspect there is provided a method for manufacturingan eye tracking device according to the device described above, whereinthe first material is placed using a 3D-printer.

According to a fourth aspect there is provided a method formanufacturing an eye tracking device according to the device describedabove, wherein the first material and/or the second material is placedusing a 3D-printer.

According to some embodiments, the method further comprises the step ofpolishing the surface of the illuminators and/or imaging module so as toremove non-transparent material from illuminator surface and/oraccomplish a polished optically equal surface.

Effects and features of the second, third and fourth aspects are largelyanalogous to those described above in connection with the first aspect.Embodiments mentioned in relation to the first aspect are largelycompatible with the second aspect, third, and fourth aspects. It isfurther noted that the inventive concepts relate to all possiblecombinations of features unless explicitly stated otherwise.

A further scope of applicability of the present invention will becomeapparent from the detailed description given below. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thescope of the invention will become apparent to those skilled in the artfrom this detailed description.

Hence, it is to be understood that this invention is not limited to theparticular component parts of the device described or steps of themethods described as such device and method may vary. It is also to beunderstood that the terminology used herein is for purpose of describingparticular embodiments only, and is not intended to be limiting. It mustbe noted that, as used in the specification and the appended claim, thearticles “a”, “an”, “the”, and “said” are intended to mean that thereare one or more of the elements unless the context clearly dictatesotherwise. Thus, for example, reference to “a unit” or “the unit” mayinclude several devices, and the like. Furthermore, the words“comprising”, “including”, “containing” and similar wordings does notexclude other elements or steps.

BRIEF DESCRIPTIONS OF THE DRAWINGS

The above objects, as well as additional objects, features andadvantages of the present invention, will be more fully appreciated byreference to the following illustrative and non-limiting detaileddescription of preferred embodiments of the present invention, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1a is a perspective view of an eye tracking device integrated in aframe of a pair of glasses where the first material is transparent.

FIG. 1b is a perspective view of an eye tracking device integrated in aframe of a pair of glasses where the first material is non-transparent.

FIG. 2 is a schematic view of an over-molded illuminator LED with firstmaterial and second material.

FIG. 3 is a schematic view of an over-molded illuminator LED with onlyfirst material.

FIG. 4 is a box diagram showing a first method for manufacturing an eyetracking device.

FIG. 5 is a box diagram showing a second method for manufacturing an eyetracking device.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which currently preferredembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided as examples to convey the scope of the invention to the skilledperson.

FIG. 1a shows an eye tracking device 1 integrated into a frame 11 of apair of glasses. Only one of the frame for the right eye is shown. Theeye tracking device comprises one or more illuminators 2, eachilluminator 2 comprising a light emitting side 3, and each illuminatorbeing connected to a first circuitry carrier 4. An imaging module 5 isconnected to a second circuitry carrier 9 and the image module 5comprises optic arrangements 10. The plurality of illuminators 2, theimaging module 5 and the circuitry carriers 4, 9 are embedded withoutgaps in a first material 6. The first material comprises openings 7 suchthat at least one of the light emitting sides of the illuminators andviewing portion 10 of the optic arrangements of the imaging module 5 arenot covered by the first material 6. In FIG. 1a the first material 6 istransparent. All illuminators 2 are in this embodiment side emitting andconnected to a single first circuitry carrier 4. The first circuitrycarrier 4 and/or the second circuit carrier 9 may be a Printed CircuitBoard PCB or a 3D molded interconnect devices 3D-MIDs.

FIG. 1b shows the same eye tracking device 1 integrated into a frame 11of a pair of glasses as in FIG. 1a where the first material 6 isnon-transparent, at least to visible light. It could however betransparent for light from illuminators irradiating in NIR. In caseswhere the frame of the glasses has no openings, the first material 6 maybe transparent for light from illuminators irradiating in NIR butnon-transparent for visible light. If the openings 7 are filled with thesecond material, the second material must be transparent for light fromilluminators. In that case the transparent properties of the firstmaterial are only important if the openings also should work asapertures for the illuminator light.

The imaging module 5 in the embodiment of FIGS. 1a and 1b is a camera,but it could be a lens-less camera or any other image module capable ofcapturing the image of reflected illuminator(s) 2 in the eye of a user.

The second circuitry carrier 9 in FIG. 1a could in another embodiment(not shown) be an integral part of the first circuitry carrier 4.

FIG. 2 is a schematic view of how the openings of the first material 6are filled with a second material 8 that is transparent for the light ofthe illuminators. The first material is in this embodimentnon-transparent to the illuminator light to shield and define possibleillumination angles of the illuminator 2. The opening 7 thus form anaperture to limit illuminator light emitting angles. This is especiallyimportant for VR applications.

In FIGS. 1a, 1b , 2 and 3 the illuminator is a LED. The illuminatorcould however be a laser, an incandescent lamp, a fluorescent materialor any other light source suitable to fit into the device. Theilluminators are Near Infrared (NIR) illuminators to not be visible tothe user and the image module thereby has to be able to capture imagesin NIR images.

In FIG. 2 the second material 8 is an optic arrangement functioning as awindow for the LED. According to a different embodiment opticarrangement built up by the second material 8 can be lens-shaped orshaped as a Fresnel lens.

FIG. 3 shows an embodiment without an optic arrangement or secondmaterial. The illuminator is a LED having its illuminating side 3un-covered towards the environment. The LED top material is thepreferably durable as e.g. PMMA. If softer LED top material is used assilico or epoxy the embodiment of FIG. 2 is preferred where the LED iscovered by the second material 8.

FIG. 4 illustrates a method for manufacturing an eye tracking device,comprising the steps S1 providing a plurality of illuminator, eachilluminator comprising a light emitting side, and each illuminator beingconnected to a first circuitry carrier, S2 providing an imaging moduleconnected to a second circuitry carrier, the imaging module comprising alens for capturing images of an eye, S3 embedding the plurality ofilluminators, the imaging module and the circuitry carriers without gapsin a first material, wherein the first material comprises openings suchthat the light emitting sides of the illuminators and the imaging modulelens are not covered by first material. The embodiment further comprisesthe step of S4 filling at least one of the openings of the firstmaterial with a second material that is transparent for the light of theilluminator. The step of embedding S3 comprises: S3 a providing a firstmold, S3 b placing the first circuitry carrier and second circuitrycarrier in the first mold, S3 c filling the empty space of the firstmold with the first material.

FIG. 5 illustrates another embodiment of a method for manufacturing aneye tracking device, comprising the steps S1 providing a plurality ofilluminator, each illuminator comprising a light emitting side, and eachilluminator being connected to a first circuitry carrier, S2 providingan imaging module connected to a second circuitry carrier, the imagingmodule comprising a lens for capturing images of an eye, S3 embeddingthe plurality of illuminators, the imaging module and the circuitrycarriers without gaps in a first material, wherein the first materialcomprises openings such that the light emitting sides of theilluminators and the imaging module lens are not covered by firstmaterial. The step of embedding comprises S3 e providing a second moldwith empty spaces aligned with the light emitting sides of theilluminators and the viewing portion of the imaging module, S3 f placingthe first circuitry carrier and second circuitry carrier to the mold, S3g filling the with the second material, such that at least the lightemitting sides of the illuminators and the viewing portion of theimaging module are embedded in second material, S3 h providing a firstmold, S3 i placing the first circuitry carrier and second circuitrycarrier in the first mold, S3 j filling the empty space of the firstmold with the first material.

The person skilled in the art realizes that the present invention by nomeans is limited to the preferred embodiments described above. On thecontrary, many modifications and variations are possible within thescope of the appended claims. For example, even though not shown in theFigures, the second material may be shaped to a lens, a Fresnel lens orany other light guiding structure. The surfaces may be polished toenhance optical properties or remove unwanted material in amanufacturing step.

Additionally, variations to the disclosed embodiments can be understoodand effected by the skilled person in practicing the claimed invention,from a study of the drawings, the disclosure, and the appended claims.

The invention claimed is:
 1. An eye tracking device comprising: one ormore illuminators, each illuminator comprising a light emitting side,and each illuminator being connected to a first circuitry carrier, animaging module connected to a second circuitry carrier, the imagingmodule comprising optical arrangements, wherein the plurality ofilluminators, the imaging module and the first and second circuitrycarriers are embedded without gaps in a first material, wherein thefirst material comprises openings such that at least one of the lightemitting sides of the illuminators and viewing portion of the opticalarrangements of the imaging module are not covered by the firstmaterial, and wherein at least one of the openings of the first materialare filled with a second material that is transparent for the light ofthe illuminators.
 2. The eye tracking device according to claim 1,wherein the first material is non-transparent to the illuminator lightand the second material is transparent to IR light but non-transparentto visible light.
 3. The eye tracking device according to claim 1,wherein all illuminators (2) are connected to a single first circuitrycarrier (4).
 4. The eye tracking device according to claim 1, whereinthe first circuitry carrier or the second circuitry carrier is a PrintedCircuit Board (PCB) or a 3D molded interconnect devices (3D-MIDs). 5.The eye tracking device according to claim 4, wherein the secondcircuitry carrier is an integral part of the first circuitry carrier. 6.The eye tracking device according to claim 1, wherein the imaging moduleis a module comprised in the group of: a camera, a lens-less camera. 7.The eye tracking device according to claim 1, wherein the openings areformed as apertures to limit illuminator light emitting angles.
 8. Theeye tracking device according to claim 1, wherein the illuminators arefront emitting to maximize light emittance in the frontal direction ofthe illuminators or side emitting to avoid light emittance in certaindirections from the illuminators.
 9. The eye tracking device accordingto claim 1, wherein the illuminators are Near Infrared (NIR)illuminators and the illuminators are a radiation source comprised inthe group of: an LED, a laser, an incandescent lamp and a fluorescentmaterial.
 10. The eye tracking device according to claim 1, wherein thesecond material is an optic arrangement.
 11. The eye tracking deviceaccording to claim 1, wherein the first material is PMMA, PC, Zeonex orABS with or without added pigments that are transparent to NIR, and/orthe second material is PMMA, PC, Zeonex or ABS with added pigments thatare non-transparent to NIR.
 12. The eye tracking device according toclaim 1, wherein the first circuitry carrier and/or the second circuitrycarrier is flexible.
 13. A method for manufacturing an eye trackingdevice, comprising the steps of: providing a plurality of illuminator,each illuminator comprising a light emitting side, and each illuminatorbeing connected to a first circuitry carrier, providing an imagingmodule connected to a second circuitry carrier, the imaging modulecomprising a lens for capturing images of an eye, embedding theplurality of illuminators, the imaging module and the circuitry carrierswithout gaps in a first material, wherein the first material comprisesopenings such that the light emitting sides of the illuminators and theimaging module lens are not covered by first material, furthercomprising the step of filling at least one of the openings of the firstmaterial with a second material that is transparent for the light of theilluminator.
 14. The method for manufacturing an eye tracking deviceaccording to claim 13, wherein the step of embedding comprises:providing a first mold, placing the first circuitry carrier and secondcircuitry carrier in the first mold, filling the empty space of thefirst mold with the first material.
 15. The method for manufacturing aneye tracking device according to claim 14, wherein the mold comprisesfirst structures for preventing the first material from covering thelight emitting side of the illuminators and a second structure forpreventing the first material from covering the imaging module.
 16. Themethod for manufacturing an eye tracking device according to claim 15,wherein the mold comprises alignment features for aligning the firststructures and the second structure with the illuminators and imagingmodule, respectively.
 17. The method for manufacturing an eye trackingdevice according to claim 16, wherein the step of embedding comprises:providing a second mold with empty spaces aligned with the lightemitting sides of the illuminators and the viewing portion of theimaging module, placing the first circuitry carrier and second circuitrycarrier to the mold, filling the mold with the second material, suchthat at least the light emitting sides of the illuminators and theviewing portion of the imaging module are embedded in second material,providing a first mold, placing the first circuitry carrier and secondcircuitry carrier in the first mold, filling the empty space of thefirst mold with the first material.
 18. The method for manufacturing aneye tracking device according to claim 13, wherein the first circuitrycarrier and/or the second circuitry carrier is flexible.